ListenerList

java.lang.Object
- org.eclipse.core.runtime.ListenerList<E>

Type Parameters:

E - the type of listeners in this list

All Implemented Interfaces:

java.lang.Iterable<E>
```
public class ListenerList<E>
extends java.lang.Object
implements java.lang.Iterable<E>
```
This class is a thread safe list that is designed for storing lists of listeners. The implementation is optimized for minimal memory footprint, frequent reads and infrequent writes. Modification of the list is synchronized and relatively expensive, while accessing the listeners is very fast. For legacy code, readers are given access to the underlying array data structure for reading, with the trust that they will not modify the underlying array.
A listener list handles the same listener being added multiple times, and tolerates removal of listeners that are the same as other listeners in the list. For this purpose, listeners can be compared with each other using either equality or identity, as specified in the list constructor.

Use an enhanced 'for' loop to notify listeners. The recommended code sequence for notifying all registered listeners of say, FooListener#eventHappened(Event), is:
```
ListenerList<FooListener> fooListeners = new ListenerList<>();
//...
for (FooListener listener : fooListeners) {
        listener.eventHappened(event);
}
 
```
Legacy code may still call getListeners() and then use a 'for' loop to iterate the Object[]. This might be insignificantly faster, but it lacks type-safety and risks inadvertent modifications to the array.

This class can be used without OSGi running.
Since:

org.eclipse.equinox.common 3.2

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`EQUALITY` Mode constant (value 0) indicating that listeners should be considered the same if they are equal.
`static int`	`IDENTITY` Mode constant (value 1) indicating that listeners should be considered the same if they are identical.

Constructor Summary

Constructors
Constructor and Description
`ListenerList()` Creates a listener list in which listeners are compared using equality.
`ListenerList(int mode)` Creates a listener list using the provided comparison mode.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`add(E listener)` Adds a listener to this list.
`void`	`clear()` Removes all listeners from this list.
`java.lang.Object[]`	`getListeners()` Returns an array containing all the registered listeners.
`boolean`	`isEmpty()` Returns whether this listener list is empty.
`java.util.Iterator<E>`	`iterator()` Returns an iterator over all the registered listeners.
`java.util.stream.Stream<E>`	`parallelStream()` Returns a parallel `Stream` over the registered listeners.
`void`	`remove(java.lang.Object listener)` Removes a listener from this list.
`int`	`size()` Returns the number of registered listeners.
`java.util.Spliterator<E>`	`spliterator()` Returns a Spliterator covering the registered listeners.
`java.util.stream.Stream<E>`	`stream()` Returns a sequential `Stream` over the registered listeners.
`java.lang.String`	`toString()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface java.lang.Iterable
forEach

- Field Detail
  - EQUALITY
```
public static final int EQUALITY
```
    Mode constant (value 0) indicating that listeners should be considered the same if they are equal.
    
    See Also:
    
    Constant Field Values
  - IDENTITY
```
public static final int IDENTITY
```
    Mode constant (value 1) indicating that listeners should be considered the same if they are identical.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - ListenerList
```
public ListenerList()
```
    Creates a listener list in which listeners are compared using equality.
  - ListenerList
```
public ListenerList(int mode)
```
    Creates a listener list using the provided comparison mode.
    
    Parameters:
    
    mode - The mode used to determine if listeners are the same.
- Method Detail
  - add
```
public void add(E listener)
```
    Adds a listener to this list. This method has no effect if the same listener is already registered.
    
    Parameters:
    
    listener - the non-null listener to add
  - getListeners
```
public java.lang.Object[] getListeners()
```
    Returns an array containing all the registered listeners. The resulting array is unaffected by subsequent adds or removes. If there are no listeners registered, the result is an empty array. Use this method when notifying listeners, so that any modifications to the listener list during the notification will have no effect on the notification itself.
    Note: Callers of this method must not modify the returned array.
    
    Note: The recommended and type-safe way to iterate this list is to use an enhanced 'for' statement, see ListenerList. This method is deprecated for new code.
    
    Returns:
    
    the list of registered listeners
  - iterator
```
public java.util.Iterator<E> iterator()
```
    Returns an iterator over all the registered listeners. The resulting iterator is unaffected by subsequent adds or removes. Use this method when notifying listeners, so that any modifications to the listener list during the notification will have no effect on the notification itself.
    
    Specified by:
    
    iterator in interface java.lang.Iterable<E>
    
    Returns:
    
    an iterator
    
    Since:
    
    org.eclipse.equinox.common 3.8
  - isEmpty
```
public boolean isEmpty()
```
    Returns whether this listener list is empty.
    
    Returns:
    
    true if there are no registered listeners, and false otherwise
  - remove
```
public void remove(java.lang.Object listener)
```
    Removes a listener from this list. Has no effect if the same listener was not already registered.
    
    Parameters:
    
    listener - the non-null listener to remove
  - size
```
public int size()
```
    Returns the number of registered listeners.
    
    Returns:
    
    the number of registered listeners
  - clear
```
public void clear()
```
    Removes all listeners from this list.
  - spliterator
```
public java.util.Spliterator<E> spliterator()
```
    Returns a Spliterator covering the registered listeners.
    The spliterator reports Spliterator.SIZED, Spliterator.SUBSIZED, Spliterator.ORDERED, and Spliterator.IMMUTABLE
    
    Specified by:
    
    spliterator in interface java.lang.Iterable<E>
    
    Returns:
    
    a spliterator for listeners
    
    Since:
    
    org.eclipse.equinox.common 3.9
  - stream
```
public java.util.stream.Stream<E> stream()
```
    Returns a sequential Stream over the registered listeners.
    
    Returns:
    
    a sequential Stream over the registered listeners.
    
    Since:
    
    org.eclipse.equinox.common 3.9
  - parallelStream
```
public java.util.stream.Stream<E> parallelStream()
```
    Returns a parallel Stream over the registered listeners.
    
    Returns:
    
    a parallel Stream over the registered listeners.
    
    Since:
    
    org.eclipse.equinox.common 3.9
  - toString
```
public java.lang.String toString()
```
    Overrides:
    
    toString in class java.lang.Object

Class ListenerList<E>

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Methods inherited from interface java.lang.Iterable

Field Detail

EQUALITY

IDENTITY

Constructor Detail

ListenerList

ListenerList

Method Detail

add

getListeners

iterator

isEmpty

remove

size

clear

spliterator

stream

parallelStream

toString